Creating the bracket set
With the Sony A7R its a simple matter of holding the shutter button down. I first started using this approach with my 5DIII and came to love it for doing handheld bracket sets while walking around in the city. The A7R offers the same flexility for shooting the bracket set. There is a menu setting that permits setting up the bracket set. From my experience with the 5DIII and Lightroom I knew I wanted a 3 frame set with minus 3EV, 0 EV and plus 3 EV. This works well with Lightroom convert the HDR Pro option for loading the files into Photoshop to create the 32 bit file. The file is saved back into the same folder and shows up in the catalog. The file has to be saved as a TIFF so Lightroom can recognize the file for editing.
Processing in Lightroom
I am currently using Lightroom 5.7 but the ability to process 32 bit floating point files has been in Lightroom since version 4.3. The 32 bit file extends the range for the develop module sliders. The Exposure slider has a range from minus 10 to plus 10 EV. Double the range for a raw file from the camera.
The Sony A7R raw files have a respectable dynamic range. Some reviews say its more than 12 EV. Creating a 6EV bracket set has the potential to extend the range significantly. One benefit this approach offers is file with no noise in the shadows while keeping subtle detail in near specular highlights.
The two bracket sets I’ve used here to illustrate Lightroom processing of the 32 bit file illustrate two common situations when shooting architecture. One has windows with sunny outside landscape along with deep shadow areas in the foreground and floor. Along with a strong gradation from sunlit interior to artificially lit interior areas. The second situation has strongly sunlit shiny white and clear foreground elements along with dark, less well lit background elements.
Keeping the outside in the windows
Here are the three bracket images as they were imported into Lightroom;
The set is what one expects from this kind of setup. The minus 3EV exposure is quite dark with even the sunlit area outside under exposed. Looking the set, it appears the 0 EV and plus 3 EV brackets have all the data necessary to create a useable floating point file. Even so, I included all three in the import into Photoshop to create the 32 bit file. Photoshop may have completed the task a little faster with just two files.
Once Photoshop completes the process, I tick the eliminate ghosts option since the images were made handheld. Then have the file open in Photoshop. Then click “save as”. The window that opens has PSD set as the default file type. That has to be changed to TIFF so that Lightroom can recognize the file. The next dialog box that opens offers several TIFF file options. I leave them at default for use on my Mac. Clicking “save” causes the file to be saved in the same folder as the original bracket set in the Lightroom catalog. Closing Photoshop and returning to Lightroom the file appears in the catalog and is ready to process.
I processed the 32 bit file in Lightroom develop module using the same steps I use for any raw processing. First I slide the highlight and shadow sliders to their full extent. Then I use the white point and black point sliders to get just a few pixels showing with the Option key pressed to show the mask. Next I go to the exposure slider and use it to get the bulk of the histogram near the center. Naturally the final placement is determined by how the image looks. Then I fine tune the white and black point to keep just a bit of true black and white. I then use the clarity slider to get some midtown punch. and finally use the contrast slider to give the image some depth. Depending on the scene I may also use the tone curve to steepen the S curve between highlight and shadow extremes.
The whole process takes about 15 seconds. Heres the 32 bit file with the processing described;
As a testement to the dynamic range the Sony A7R can capture, here is the 0EV bracket frame with essentially the same slider settings. I pasted them from the 32 bit file to the 0EV file and then adjusted, mostly the exposure slider, to get the final result.
Keeping Sunlit Highlights with dark background
Here are the three bracket files;
With this bracket set the plus 3 EV file is necessary to get enough detail in the back of the room. While the minus 3 EV file is required to keep detail in the white cups and glasses that are sun drenched in the foreground.
I used the same technique for this image. There was a bit more tweaking required to get the cups and glasses looking OK because of the specular highlights along with white detail.
The sunny outside visible through the windows in the background looks the way I want it to for this kind of shot. i.e. bright but not blown out.
With this set, the o EV file was not usable because the highlights in the white cups are blocked up.
These two example are a good illustration of why I bracket all my shooting when doing architecture. Many times I can get the image I want using one of the three brackets. Most often the 0 EV frame. However, there are times when I need the 32 bit file to make sure I can keep detail in the whites and blacks as they go to the extreme. Lightroom’s ability to process a 32 bit file with extended range in the develop module means I rarely have to use Photoshop. This means a much faster processing workflow.
Using this technique does not preclude using strobes or speedlites to help get the lighting I want when shooting interiors, but I have found I can do it much less often. The final decision depends on a lot of factors.